The present invention relates to a method for the preparation of a sodium salt of 1-alkyne or, more particularly, to a method for the preparation of a sodium salt of 1-alkyne represented by the general formula ##STR2## in which R.sup. and R.sup.2 each denote a hydrogen atom or a monovalent hydrocarbon group having no aliphatic unsaturation, by the reaction of a 1,2-alkadiene of the formula ##STR3## in which R.sup.1 and R.sup.2 each have the same meaning as defined above, with metallic sodium.
In the prior art, it is well known that a sodium salt of 1-alkyne of the above general formula (I), which is a useful intermediate for the synthetic preparation of various organic compounds such as 1-alkynes, can be prepared by the reaction of a corresponding 1,2-alkadiene of the general formula (II) above with metallic sodium. For example, 1,2-butadiene is reacted with metallic sodium of wire-like form in an inert reaction medium under a superatmospheric pressure, e.g. 10 to 20 kg/cm G, to give butynyl sodium (see, for example, Japanese patent Disclosure No. 50-18406). This method is necssarily carried out in a pressurized vessel, e.g. autoclave, because the reaction is carried out under a superatmospheric pressure. Further, the reaction velocity in the above known method is relatively low and the yield of the desired butynyl sodium rarely exceeds 50% based on the 1,2-butadiene used in the reaction.